Conventionally, in a weft knitting machine, a plurality of knitting needles are disposed adjacent to each other to a needle bed, and knitting of a fabric is executed in a manner that a knitting yarn is fed while a knitting operation is sequentially executed with the knitting needles. The knitting operation sequentially executed with the knitting needles is executed by a cam mechanism for knitting mounted on a carriage moving along the needle bed, and a carrier brought by the carriage feeds the knitting yarn to the knitting needles.
FIG. 15 shows a schematic configuration of a mechanism in which a carriage brings a carrier. In a V-bed weft knitting machine in which a pair of needle beds located at the front and back confront at a needle bed gap, a yarn guide rail 1 serving as a guide rail is constructed above the needle bed gap. A bringing pin 3 is caused to appear and disappear in a part where a bridge 2 connecting the carriages disposed to the front and back needle beds crosses the yarn guide rail 1, thereby being capable of selectively bringing a carrier 4 serving as a moving member capable of traveling along the yarn guide rail 1. The carrier 4 is provided with a bringing recessed portion 5 with which the projected bringing pin 3 can engage.
A yarn feeding position to feed a knitting yarn to the knitting needle while knitting a fabric is set on a way in which the knitting needle is caused to retreat from the needle bed gap after being caused to advance to the needle bed gap by the knitting cam mounted on the carriage. In the case of using the knitting cam in common to move the carriage in one direction and move in the other direction, there is a need to switch the yarn feeding position to a different position with reference to the position of the knitting cam, in accordance with a moving direction of the carriage. In order that a yarn is fed to a position displaced a given distance with respect to the knitting cam in accordance with the moving direction of the carriage, the bringing recessed portion 5 has a specified width. When the carriage reverses the moving direction, a position in which the bringing pin 3 abuts against the bringing recessed portion is switched from one to the other between a right end 5a and a left end 5b of the bringing recessed portion 5.
When the bringing pin 3 is caused to subside from the side of the carriage that is moving along the knitted fabric, bringing of the carrier 4 by the carriage is stopped, and in a case where the carriage is moving, the carrier 4 persists in moving along the yarn guide rail 1 as well through inertia. However, it is desired that the carrier 4 remain in a position where the bringing has been stopped. This is because in a case where the carrier 4 moves before stopping from the position where engagement of the bringing pin 3 with the bringing recessed portion 5 has been released, the position becomes ambiguous when the carrier 4 is brought next with the bringing pin 3 projected.
In order that the carrier 4 having stopped being brought by the carriage is immediately stopped on the yarn guide rail 1, sliding resistance is applied in-between the carrier 4 and the yarn guide rail 1. The sliding resistance may be applied mechanically. The sliding resistance may be applied magnetically (for example, refer to Japanese Examined Patent Publication JP-B2 2858768).
Since the sliding resistance between the carrier 4 and the yarn guide rail 1 increases a moving load on the carriage when the carriage brings the carrier 4, it is preferred that the sliding resistance be small. However, there is a possibility that after the bringing stops, a distance necessary for the carrier 4 to stop gets long and a problem like an overrun occurs. The applicant of the present application proposed a technique of, in the case of utilizing magnetism in a weft knitting machine, using a magnetic circuit that includes a permanent magnet and an electromagnet and changing the strength of magnetism by passing pulsed electric current through the electromagnet (for example, refer to Japanese Unexamined Patent Publication JP-A 3-280405 (1991)).
In the case of only applying the sliding resistance in-between the carrier and the guide rail as disclosed in JP-B2 2858768, a load on the carriage that is bringing the carrier increases. In the case of mechanically applying the sliding resistance, wear-out is easy to occur as well. Further, when the carriage reverses, a position against which the bringing pin abuts in the bringing recessed portion with which the bringing pin engages changes.
For example, in FIG. 15, a case where the carriage moves rightward and knitting of one course ends, and the carriage moves leftward in knitting of the next course, will be assumed. While the carriage is moving rightward, the bringing pin 3 abuts against the right end 5a of the bringing recessed portion 5. Even if the carriage stops, the carrier 4 persists in moving more rightward through inertia. In a case where the sliding resistance is small, the carrier 4 continues movement rightward. When the bringing pin 3 is in a projected state, the left end 5b of the bringing recessed portion 5 abuts against the bringing pin 3, and the movement of the carrier 4 stops. When the bringing pin 3 is not projected, there is a possibility that the carrier 4 moves more rightward, that is, an overrun occurs. In a case where the overrun occurs, the bringing recessed portion 5 is away from the bringing pin 3 and cannot bring the carrier 4 even if the bringing pin 3 is projected so as to move the carriage leftward.
In a case where the sliding resistance of the carrier 4 to the yarn guide rail 1 is large, it is possible to stop the carrier 4 within a range where the carrier 4 can be brought by the bringing pin 3 at least when the carriage reverses the moving direction. However, since the carrier 4 is brought after the bringing pin 3 abuts against the left end 5b of the bringing recessed portion 5, an impact is generated when the bringing pin 3 abuts against the left end 5b. This impact gets larder as the sliding resistance of the carrier 4 to the yarn guide rail 1 is larger. It is feared that this impact causes a noise, and that repetition of the impact causes damage. Further, in the case of increasing a moving speed of the carriage in order to increase productivity, an impact and a noise get larger.
In the case of using an electromagnet as disclosed in JP-A 3-280405, it is possible to control applied sliding resistance by utilizing magnetism. However, it is difficult to mount a configuration including the electromagnet on the aforementioned carrier 4. It is desired that the carrier 4 traveling along the yarn guide rail 1 be as small in size and light in weight as possible. Mounting the configuration including the electromagnet on the carrier 4 results in increase of the weight and upsizing. Moreover, it becomes necessary to supply electric power for exciting the electromagnet.